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#include "precomp.hpp"

namespace cv {


void write(FileStorage& fs, const string& objname, const vector<KeyPoint>& keypoints) {
	WriteStructContext ws(fs, objname, CV_NODE_SEQ + CV_NODE_FLOW);

	int i, npoints = (int)keypoints.size();
	for ( i = 0; i < npoints; i++ ) {
		const KeyPoint& kpt = keypoints[i];
		write(fs, kpt.pt.x);
		write(fs, kpt.pt.y);
		write(fs, kpt.size);
		write(fs, kpt.angle);
		write(fs, kpt.response);
		write(fs, kpt.octave);
		write(fs, kpt.class_id);
	}
}


void read(const FileNode& node, vector<KeyPoint>& keypoints) {
	keypoints.resize(0);
	FileNodeIterator it = node.begin(), it_end = node.end();
	for ( ; it != it_end; ) {
		KeyPoint kpt;
		it >> kpt.pt.x >> kpt.pt.y >> kpt.size >> kpt.angle >> kpt.response >> kpt.octave >> kpt.class_id;
		keypoints.push_back(kpt);
	}
}


void KeyPoint::convert(const std::vector<KeyPoint>& keypoints, std::vector<Point2f>& points2f,
					   const vector<int>& keypointIndexes) {
	if ( keypointIndexes.empty() ) {
		points2f.resize( keypoints.size() );
		for ( size_t i = 0; i < keypoints.size(); i++ ) {
			points2f[i] = keypoints[i].pt;
		}
	} else {
		points2f.resize( keypointIndexes.size() );
		for ( size_t i = 0; i < keypointIndexes.size(); i++ ) {
			int idx = keypointIndexes[i];
			if ( idx >= 0 ) {
				points2f[i] = keypoints[idx].pt;
			} else {
				CV_Error( CV_StsBadArg, "keypointIndexes has element < 0. TODO: process this case" );
				//points2f[i] = Point2f(-1, -1);
			}
		}
	}
}

void KeyPoint::convert( const std::vector<Point2f>& points2f, std::vector<KeyPoint>& keypoints,
						float size, float response, int octave, int class_id ) {
	for ( size_t i = 0; i < points2f.size(); i++ ) {
		keypoints[i] = KeyPoint(points2f[i], size, -1, response, octave, class_id);
	}
}

float KeyPoint::overlap( const KeyPoint& kp1, const KeyPoint& kp2 ) {
	float a = kp1.size * 0.5f;
	float b = kp2.size * 0.5f;
	float a_2 = a * a;
	float b_2 = b * b;

	Point2f p1 = kp1.pt;
	Point2f p2 = kp2.pt;
	float c = (float)norm( p1 - p2 );

	float ovrl = 0.f;

	// one circle is completely encovered by the other => no intersection points!
	if ( min( a, b ) + c <= max( a, b ) ) {
		return min( a_2, b_2 ) / max( a_2, b_2 );
	}

	if ( c < a + b ) { // circles intersect
		float c_2 = c * c;
		float cosAlpha = ( b_2 + c_2 - a_2 ) / ( kp2.size * c );
		float cosBeta  = ( a_2 + c_2 - b_2 ) / ( kp1.size * c );
		float alpha = acos( cosAlpha );
		float beta = acos( cosBeta );
		float sinAlpha = sin(alpha);
		float sinBeta  = sin(beta);

		float segmentAreaA = a_2 * beta;
		float segmentAreaB = b_2 * alpha;

		float triangleAreaA = a_2 * sinBeta * cosBeta;
		float triangleAreaB = b_2 * sinAlpha * cosAlpha;

		float intersectionArea = segmentAreaA + segmentAreaB - triangleAreaA - triangleAreaB;
		float unionArea = (a_2 + b_2) * (float)CV_PI - intersectionArea;

		ovrl = intersectionArea / unionArea;
	}

	return ovrl;
}

}
